The Fission Yeast Pre-mRNA-processing Factor 18 (prp18(+)) Has Intron-specific Splicing Functions with Links to G(1)-S Cell Cycle Progression

Vijaykrishna, Nagampalli and Melangath, Geetha and Kumar, Rakesh and Khandelia, Piyush and Bawa, Pushpinder and Varadarajan, Raghavan and Vijayraghavan, Usha (2016) The Fission Yeast Pre-mRNA-processing Factor 18 (prp18(+)) Has Intron-specific Splicing Functions with Links to G(1)-S Cell Cycle Progression. In: JOURNAL OF BIOLOGICAL CHEMISTRY, 291 (53). 27387+.

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Abstract

The fission yeast genome, which contains numerous short introns, is an apt model for studies on fungal splicing mechanisms and splicing by intron definition. Here we perform a domain analysis of the evolutionarily conserved Schizosaccharomyces pombe pre-mRNA-processing factor, SpPrp18. Our mutational and biophysical analyses of the C-terminal alpha-helical bundle reveal critical roles for the conserved region as well as helix five. We generate a novel conditional missense mutant, spprp18-5. To assess the role of SpPrp18, we performed global splicing analyses on cells depleted of prp18(+) and the conditional spprp18-5 mutant, which show widespread but intron-specific defects. In the absence of functional SpPrp18, primer extension analyses on a tfIId(+) intron 1-containing minitranscript show accumulated pre-mRNA, whereas the lariat intron-exon 2 splicing intermediate was undetectable. These phenotypes also occurred in cells lacking both SpPrp18 and SpDbr1 (lariat debranching enzyme), a genetic background suitable for detection of lariat RNAs. These data indicate a major precatalytic splicing arrest that is corroborated by the genetic interaction between spprp18-5 and spprp2-1, a mutant in the early acting U2AF59 protein. Interestingly, SpPrp18 depletion caused cell cycle arrest before S phase. The compromised splicing of transcripts coding for G(1)-S regulators, such as Res2, a transcription factor, and Skp1, a regulated proteolysis factor, are shown. The cumulative effects of SpPrp18-dependent intron splicing partly explain the G1 arrest upon the loss of SpPrp18. Our study using conditional depletion of spprp18(+) and the spprp18-5 mutant uncovers an intron-specific splicing function and early spliceosomal interactions and suggests links with cell cycle progression.

Item Type:	Journal Article
Publication:	JOURNAL OF BIOLOGICAL CHEMISTRY
Additional Information:	Copy right for this article belongs to the AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3996 USA
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	17 Feb 2017 04:44
Last Modified:	17 Feb 2017 04:44
URI:	http://eprints.iisc.ac.in/id/eprint/56249

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